More or less with the coins. Hold up one coin and show your child. Hold up a second one and ask them whether that second coin is more or less than the previous. Strat easy by doing different colour coins then moving on to same colours. You could also make it a game. You and your child close your eyes and choose a coin. You look at your coins and then show one another. The biggest or smallest coin wins!
Extra challenge: Adding coins together to come to a total, using 1, 2, 5 and 10p coins. Your child needs to buy their dinner or some iPad time. Work with them to find out how to make 3p, 4p, 7p etc.